For some time now, gas springs have been used as an elastic force-limiting element in sheet metal stamping processes.
Manufacturer requirements, both for producing more parts in the same amount of time and for producing more complex parts, have led to the control and increase of working speeds of all the die elements, including those of gas springs.
The need to control the speed of the elements, tools and machines used to obtain the final part is becoming increasingly frequent among stamped part manufacturers, due to the increased complexity thereof. Advances in presses allow speeds at each point to be governed as required for each type of part. Also in accordance with the design thereof, the gas spring rod must not return solidarily to the press, but must rather be delayed and said delay be controlled. In this manner, it is possible to form a part in a smaller number of stages, due to being able to withdraw said part without being damaged by the elements associated to the gas spring rods which have allowed deformation thereof.
Gas spring delay systems allow the rod to recover its position within a certain time period, longer than it takes for the press to return to its original position, at constant speed, once the press withdrawal process has started. Additionally, start of recovery can even be delayed by keeping the rod completely stopped (WO90/15267) and subsequently returning at constant speed.